SODIUM AMALGAMATION. 
















SODIUM AMALGAMATION, 


IN A LETTER FROM 



HENRY WURTZ TO PROFESSOR B. SILLIMAN. 



[From the American Journal of Science and Arts, Vol. XLI, Mar., 1866.] 



NEW HAVEN: 

PRINTED BY E. HAYES, 426 CHAPEL 8 T, 

1866 . 































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6 - /g.S'A 3 



















ON SODIUM AMALGAMATION. 


In the opinion of yourself and others upon whose judgment 
I rely, the time has arrived for the promulgation of the discov¬ 
eries made by me, now many years since, of certain new proper¬ 
ties of the alkali-metals, rendering them of value in the amalga¬ 
mation of ores of the precious metals. 

You are aware that, pending the repeated investigations 
which I have conducted upon this important subject, I have 
made communications of my results, both oral and written, from 
time to time to many persons, yourself among the number; but 
that until the latter part of the year 1864, no final step was 
taken to place these discoveries before the public in a tangible 
form. On the 27th of December, 1864, a patent of the U. S. 
Government was granted to me for specified modes of applying 
the said discoveries; the specification having been at my request 
retained on file in the Patent Office for six months (as the new 
.patent law permits); so that the expiration of the term of this 
patent did not commence until the 27th of June, 1865. 

It appears, however, that my frequent communications had 
led to wide discussion of the remarkable phenomena involved, 
phenomena which I seldom hesitated to exhibit, even to the 
most casual acquaintances, taking only the precaution of silence 
as to the agent employed (the sodium); and the inevitable con¬ 
sequence has been the occupation of other minds with the sub¬ 
ject, both here and abroad. In fact, since the issue of my 
patent, I am informed that several applications (necessarily 
fruitless) have been made at Washington by others for patents 
covering some or all of my uses of the alkali-metals; and an 
English patent has been procured in the name of the eminent 
chemist Wm. Crookes, dated Aug. 12, 1865 (about eight months 
subsequent to the filing of my specification at Washington); 
of the specification of which I have procured a copy, and find 
it to present a remarkable similarity to my own. Moreover, 
I frequently find allusions and statements relating to this sub¬ 
ject, generally more or less imperfect and obscure, in the public 
prints throughout the world. 

It has clearly, therefore, become incumbent upon me—if only 
as a matter of justice to the mining community and others in¬ 
terested— to furnish authentic information as to what has 



4 


H. Wurtz on Sodium Amalgamation . 


actually been done, and what it is proposed to do. I have, 
therefore, prepared an abstract of my specification, embodying 
in a condensed form such portions of its substance as appear of 
present importance to miners and metallurgists. 

Other portions of the subject-matter of the specification will 
form a sufficiently voluminous, and I hope interesting, topic of 
a future communication ; as, for instance, my new modes of 
preparing amalgams of the alkali-metals in large masses with 
any desired rapidity, safety and economy ; and which you, with 
other chemical scientists who have witnessed its operation, deem 
important in a purely scientific view; as involving novel phe¬ 
nomena, and illustrating molecular laws obscurely seen *at 
present. 

AVith a few explanatory observations, which seem needed, I 
shall conclude. I have found it necessary, for practical pur¬ 
poses, to prepare three different grades of the sodium amalgams, 
differing from each other in their proportions of sodium about 
as the numbers 1, 2 and 3 ; and which I designate accordingly. 

A few lines, also, regarding the term “ magnetic amalgams, 5 ' 
which not a few will deem fantastic, and as suggesting un¬ 
authorized analogies. I hope to show, however, at some other 
time, that in applying the term I have followed the dictates of 
reason, and even the direct path of the modern leaders in cos- 
mical dynamics, the apostles of the doctrine of correlation of 
physical forces; and that the analogical element which I find is 
that between attractive and repulsive antagonistic force which 
exerts a chemical, or rather an elementary discrimination between 
bodies at insensible distances, and the antagonistic force of mag- 
netio attraction and repulsion, which is so eminent an example 
of a similar elementary discrimination, though at sensible dis¬ 
tances also. No one (to offer an illustration nearly, though not 
quite perfect) doubts the intimate relation between radiated and 
eonvected heat, although the one propagates itself throughout 
the universe of space, whilst the other is susceptible only of dif¬ 
fusion throughout insensible distances, from molecule to molecule. 

More of this, however, hereafter. The term, from its conven¬ 
ience alone, will doubtless come into extensive use, as a techni¬ 
cal term, among those who are most concerned in the utiliza¬ 
tion of the magnetic amalgams. 

39 Nassau St., New York, January 15, 1866. 

Specification. 

My invention consists: In imparting to quicksilver * a 
greatly enhanced adhesion, attraction, or affinity for other metals 
and for its own substance; by adding to it a minute quantity 
of one of the highly electro-positive metals * sodium, 
potassium * etc. 


5 


H. Wurtz on Sodium Amalgamation. 

My invention * is applicable: 

1st. In all arts and operations in which amalgamation by 
quicksilver can be made available to separate or extract gold, 
silver or other precious metals from their ores. 

* # 

3d. In all operations in which amalgamation by quicksilver, 
in conjunction with reducing metals, such as iron or zinc, can 
be made available in recovering metals from their soluble or in¬ 
soluble saline compounds; such as silver from its sulphate, 
chlorid or hyposulphite; lead from its sulphate or chlorid ; gold 
from its chlorid or other solution. 

* # 

8th. In the mercurization of metallic surfaces in general; for 
instance, in the amalgamation of the surfaces of zinc in voltaic 
batteries; of the surfaces of copper plates, pans, etc., used in 
the saving of gold from its ores; * * 

9th. In the more convenient transportation of quicksilver, by 
the reduction thereof into solid forms. 

x * 

I shall now proceed to the description of those special and 
peculiar qualities of these amalgams of the alkali-metals which 
I have discovered, and which have led to my new uses of them 
in the chemical and metallurgic arts. 

A quantity of one of the magnetic amalgams, dissolved in 
one hundred times its weight or more of quicksilver, communi¬ 
cates to the whole a greatly enhanced power of adhering to 
metals ; and particularly to those which, like gold and silver, 
lie toward the negative end of the electro-chemical scale. This 
power of adhesion, in the case of these two metals, is so great, 
that the resistance which I have found their surfaces, when in 
the native state, usually oppose to amalgamation (a resistance 
which is much greater and more general than has been hitherto 
recognized, and which is due to causes as yet undiscovered, or 
at least uninvestigated) is instantly overcome; whether their 
particles be coarse, fine, or even impalpable. Even an artificial 
coating of oil or grease (which is such an enemy to amalgama¬ 
tion that the smoke of the miners’ lamps is pronounced highly 
detrimental in gold and silver mines) forms no obstacle to im¬ 
mediate amalgamation by this magnetic quicksilver. The atoms 
of the quicksilver are, as it would seem, put into a polaric con¬ 
dition by a minute addition of one of those metals which range 
themselves toward the electro-positive end of the scale; so that 
its affinity for the more electro-negative metals is so greatly ex¬ 
alted that it seizes upon, and is absorbed by, their surfaces in¬ 
stantaneously ; just as water is absorbed by a lump of sugar or 
other jDorous substance soluble in it. 


6 H. Wurlz on Sodium Amalgamation. 

Such quicksilver (unlike ordinary quicksilver) even adheres 
strongly to surfaces of iron, steel, platinum, aluminum and an¬ 
timony; an adhesion which, however, as I have discovered, in 
the case of these live metals is not of the nature of a true amal¬ 
gamation, there being no penetration whatever into the sub¬ 
stance of the metal; so that the superficially adherent magnetic 
quicksilver may be readily wiped off clean, just as water may 
be from glass. The only metal I have as yet found, which can¬ 
not be enfilmed by the use of the magnetic amalgam, is mag¬ 
nesium. 

I shall now specify the details of my various new and useful 
applications of the alkali-metals : 

I. Applications of the magnetic amalgams to working the ores of the 

precious metals. 

My improvement in methods of amalgamating gold and silver 
ores consists in adding from time to time to the quicksilver used 
in amalgamation, about one-hundredth part, or less, of its weight 
of one of the magnetic amalgams. The frequency with which 
the amalgam is to be added cannot be exactly specified, as it 
will be found to depend more or less on a multitude of circum¬ 
stances ; such, for instance, as the temperature, the purity of the 
water and the quantity of water used, the ratio borne by the 
surface of the quicksilver to its mass, the amount and mode of 
agitation of the quicksilver, the nature of the process and of the 
apparatus used, the character of the ore, the strength of the 
amalgam, etc., etc.; so that this important point can only be de¬ 
termined by experience in each case. Some general directions 
may, however, be derived from the experiments which have 
been made. It has been found that very much less sodium is 
requisite in those cases in which much water is employed, and 
that water frequently renewed; for instance, in the rifles of a 
sluice, and in all forms of amalgamators through which a con¬ 
tinual current of fresh water is kept running; mercurial solu¬ 
tions of sodium, as I have discovered, being little affected by 
water which is free from acid, alkaline, or saline impurities. In 
those cases, however, in which little water is employed, and es¬ 
pecially when the ore and quicksilver are ground up together 
into a “slum” or slime, this water soon becomes alkaline, and 
an oxydation of the sodium sets in, necessitating its frequent 
renewal. In such cases, therefore, the following manipulation 
is recommended : The whole amount of quicksilver to be used 
for working up a batch of slime, say 50 pounds, is magnetized 
by dissolving in it one per cent of amalgam No. 2; or better, 
two per cent of the soft amalgam No. 1, which dissolves more 
readily; half of the whole, or 25 pounds, is then thrown into 


7 


H. W urtz on Sodium Amalgamation, 

the mill with the ore at first, and, as the incorporation proceeds, 
certain fractions of the other half are gradually added, at inter¬ 
vals of time varying according to circumstances, until the whole 
has been added. If, as is usual, the quicksilver is a portion 
which has been separated from the slime of a previous operation, 
it will usually retain some sodium, and therefore will require 
fresh amalgam in proportionately smaller quantity. 

In sluicing operations the soft amalgam No. 1 is most suit¬ 
able, on account of its ready solubility in mercury; and in these 
cases it is practicable to test the quicksilver in the rifles and 
ascertain when the magnetic quality requires restoration, by 
throwing in a few grains of gold-dust. Similar tests are easily 
applied to slimes, and in amalgamating methods generally, a slip 
of tarnished sheet copper being a very suitable agent for such 
testings. 

It may be remarked in passing, that the amalgam No. 1 is at 
any time easily prepared from No. 2, by melting it in an iron 
ladle with about its own weight of quicksilver, or from No. 3, 
by melting with twice its weight; considerable time, however, 
being requisite, in the case of No. 3, to produce the additional 
combination. In copper-plate amalgamation, that is, in those 
cases in which auriferous materials are brought into contact with 
amalgamated metallic surfaces, it is better to substitute altogether 
for quicksilver itself (both in the first coating of the metallic 
surfaces, and in any subsequent additions of quicksilver made) 
the pasty amalgam No. 1. In these modes of amalgamation 
great economy in wear and tear of apparatus, as well as in 
first cost, is effected by using, in connection with the magnetic 
amalgam, plates or surfaces of iron instead of copper. The 
power of coating or enfilming iron renders the amalgams in fact 
peculiarly valuable in every form of arrastra, drag-mill, or other 
apparatus for amalgamation which has internal surfaces of iron, 
these surfaces becoming coated over with quicksilver, and thus 
immensely extending its chances of contact with those particles 
of gold which are so fine as to remain suspended in the water. 

Other important devices arise out of this power of enfilming 
iron surfaces, such as the keeping of iron surfaces of stamps, 
and of other apparatus used in crushing ores continually coated 
with quicksilver. Quicksilver possessed of the magnetic quality 
may be kept dropping or trickling upon the surfaces of crushing- 
rollers; or in those crushers in which iron balls are used, the 
surfaces of these balls may be kept enfilmed. In like manner 
as the adhesion of quicksilver to other metals is exalted by the 
alkali-metals, so, also, as I have discovered, is its cohesion with 
itself greatly increased. It is rendered more viscid, more diffi¬ 
cult to divide mechanically, and when thus divided runs 
together again instantly upon contact. Hence arise new results 


8 


II. Wurtz on Sodium Amalgamation. 


of incalculable value. For instance, the so-called “flouring” or 
granulation of the quicksilver, which in the amalgamation of 
ores always occasions so great losses, both of the quicksilver 
itself and of its amalgams with the precious metals, is reduced 
to a minimum or altogether prevented. 

The recovery of floured quicksilver and amalgams from 
slimes and similar mixtures is also greatly facilitated and accel¬ 
erated thereby. For this purpose some strongly magnetized 
quicksilver is thrown into the separator. Such slimes may 
even be operated upon with advantage by the ordinary process 
of 'panning by hand; a little magnetic quicksilver being thrown 
into each pan and stirred about at first for a few moments with 
the hand, which will collect together and incorporate all the 
scattered globules of auriferous amalgam. In fact, in all pan¬ 
ning operations, even upon the pay-dirt of placer diggings, 
much labor, gold, and time may in this way be saved. 

It is necessary to specify an important precaution applicable 
in some cases in which magnetic amalgams are used, and par¬ 
ticularly in those cases in which the ore is ground or agitated 
with quicksilver in contact with metallic iron. This arises from 
the liability of the adhesion of some abraded particles of iron 
to the amalgam. The following plan is therefore recommended 
in these cases: The amalgam, after separation from the excess 
of quicksilver, and before retorting, is fused in an earthen dish 
or iron ladle (with addition of a little quicksilver, if necessary, 
to make it more fluid), and the iron, which will rise and form a 
scum on the surface, is skimmed off. The excess of quicksilver 
may then, after cooling, be again separated from the amalgam 
in the usual way. Any amalgam which may adhere to the 
iron-scum is readily detached therefrom by boiling in water to 
remove the sodium. This process depends on the simple fact 
that the adhesion to the iron totally disappears with the extrac¬ 
tion of the last traces of sodium from the quicksilver. In fact, 
it is possible to remove all the iron from the amalgam by 
boiling directly in water, without any previous fusion; more 
particularly if the water be made somewhat acid or alkaline. 
The presence of iron in a sample of amalgam is readily detected 
by the magnet, which instrument may be sometimes used to 
advantage also in separating intermixed iron from amalgam, 
after all sodium has been extracted from the latter. There are 
still other metals which will usually be found adherent to the 
amalgam when sodium has been used ; such as platinum and 
osmiridium. These, like iron, immediately detach themselves 
on the removal of the sodium by boiling the diluted amalgam 
in water. A mixture of platinum or osmiridium, or both, with 
iron, may of course be freed from the latter by the magnet. It 
will generally be found desirable, as in other cases where quick- 


9 


Hi Wurtz on Sodium Amalgamation. 

silver is used and ores containing arsenic or sulphur operated 
upon, to remove as much as practicable of the arsenic or 
sulphur by previous roasting or other chemical treatment. 

* * 

HI .—Applications to the recovery of metals from their saline compounds. 

In the common operation of reducing silver to an amalgam 
from its native or artificial chlorid, or from its sulphate, by the 
action of metallic iron or zinc in conjunction with quicksilver, 
immense advantage arises from the use of the magnetic amal¬ 
gams, especially in the reduction of the time occupied to a frac¬ 
tion of that heretofore required. This applies as well to ores in 
which the silver occurs naturally as chlorid, bromid or iodid, as 
to those in which the silver has been previously converted into 
chlorid, or sulphate, or both, by roasting with common salt or 
otherwise; and to chlorid which has been precipitated from so¬ 
lution. * * * 

When gold has been obtained in solution, either from ores or 
from other materials, by the action of chlorine, aqua-regia, cyanid 
of potassium, or any other solvent, also when silver has been 
obtained in solution, in hyposulphites or otherwise, the most 
rapid and thorough mode of saving these metals will be found 
to be their conversion into amalgams, by precipitation with me¬ 
tallic iron in contact with magnetic quicksilver, more especially 
when the solutions are dilute. * * * 

The greater rapidity and perfection of the precipitation, in 
these cases, are obviously due to the absolute contact at once es¬ 
tablished with the iron surfaces by the magnetic quicksilver, and 
the perfect and powerful voltaic circuits thus kept up constantly 
throughout the two metals and the solution. 

* * 

VIII .—Applications to the Mercurializing of Metallic Surfaces in general. 

In all cases in which it is an object to save time and labor in 
the coating of surfaces of other metals with quicksilver, * * * 
the magnetic amalgams come into play; * * * 

By virtue of the adhesion to iron and other non-amalgamable 
metals imparted by the magnetic amalgams, I am enabled to 
apply quicksilver, or fluid or pasty amalgams, to any metallic 
surface, with great rapidity and facility, with a brush, after the 
fashion of a paint; the material of such brush being fine wire of 
iron, steel, aluminum, or platinum. Of these the material most 
generally suitable is the finest steel wire, tempered to about a 
spring-temper, or somewhat softer; and tne most generally use¬ 
ful form for such brushes, is that of a flat varnish or white-wash 

brush. . 

Among the important uses of such brushes may be instanced; 

2 


10 


H. Wurtz on Sodium Amalgamation. 

the amalgamation of copper (or iron) plates used in saving gold 
from ores; * * *. Another valuable use is the recovery of 
quicksilver which has been spilled or scattered in the form of 
globules; such a flat brush, saturated with magnetic quicksilver, 
instantly collecting, incorporating, and sucking up the scattered 
globules, even from the most irregular surface. 

The same principle of adhesion of magnetic amalgams to a 
brush of steel wire, is applicable, in many obvious ways, to the 
separation of metals from ores, and of granulated or floured 
quicksilver from ores and slimes, etc. 

* * 

IX .—Applications to the Transportation of Quicksilver. 

The ordinary mode of packing and transporting quicksilver 
in bulk, is very expensive and troublesome; and in its ordinary 
form its transfer from one vessel into another is accompanied by 
great liability to loss. It will therefore be found very conven¬ 
ient and useful to possess simple, cheap and practicable modes, 
such as those described above, of converting it into solid forms, 
susceptible of transportation in vessels of lighter and cheaper 
material than the ordinary wrought-iron bottles; such, for in¬ 
stance, as glass or earthen ware jars, wooden kegs, bags or bot¬ 
tles, or other envelops of caoutchouc or gutta-percha, etc., etc. 

This plan also enables quicksilver to be packed, stored, trans¬ 
ported and sold in convenient forms; such as bars, ingots, cyl¬ 
inders, blocks, cubes, spheres, or pellets, of definite sizes and 
weights, the convenience of which for many uses, and particu¬ 
larly for that of miners, is at once obvious. When the quicksil¬ 
ver is to be used in any of the arts above specified, it will then 
be already in a suitable condition, or will merely require admix¬ 
ture with some fluid quicksilver; and when to be used as pure 
quicksilver, the sodium may be removed by throwing the solid 
amalgam in fragments into hot water, preferably mixed with a 
little sulphuric or acetic acid. 

The modes of packing such ingots, for preservation and trans¬ 
portation, are already sufficiently set forth in a preceding para¬ 
graph. 

Claims .—The claims attached to this specification are twenty- 
three in number ; and those only are here given which directly 
concern the miner and amalgamator. 

What I claim as my inventions are :— 

1st. The combination with quicksilver, when used for the ex¬ 
traction by amalgamation of any metal or metals from ores, 
slimes, and mixtures with other materials; of metallic sodium, 
or metallic potassium, or any other highly electro-positive metal 
equivalent in its action thereto; as above set forth. 


11 


H. Wurtz on Sodium Amalgamation . 

2d. In those amalgamators in which amalgamated plates of 
copper or other metal are used ; the substitution therefor of plates 
or surfaces of iron, coated with quicksilver combined with sodi¬ 
um, or other highly electro-positive metal; as above set forth. 

3d. The coating of iron surfaces, between or under which 
ores or other materials are crushed, with quicksilver combined 
with sodium, or other highly electro-positive metal; as above 
set forth. 

4th. The prevention of the granulation or flouring of quick¬ 
silver, when used in any method of amalgamating ores or other 
materials; by addition thereto of sodium, or other highly electro¬ 
positive metal; as above set forth. 

5th. The separation of intermixed iron from double amalgams 
of gold and sodium, or of silver and sodium; by fusion with 
excess of quicksilver and skimming; as above set forth. 

6th. The separation of intermixed iron, platinum, osmiridium, 
and other non-amalgamable metals, from amalgams containing 
sodium or its equivalent; by action thereupon of water or other 
oxydating liquid ; as above set forth. 

7th. The separation of intermixed iron from amalgams con¬ 
taining sodium or its equivalent, or from any metal or metals 
extracted from such amalgams; by magnets, either permanent 
or electro-magnetic; as above set forth. 

8th. The combination with quicksilver, when used in con¬ 
junction with iron or other reducing metals, for reducing to an 
amalgam, silver from its chlorid or other compound, or any 
other metal from any saline compound or solution; of sodium, 
or other highly electro-positive metal; as above set forth. 

* * 

12th. In all cases in which metallic surfaces, such as copper 
plates, the zincs of voltaic batteries, etc., are to be amalgamated; 
the use of quicksilver combined with sodium, or other highly 
electro-positive metal; as above set forth. 

13th. The more rapid and convenient application of quicksil¬ 
ver to surfaces with metallic brushes; by virtue of its previous 
combination with sodium, or other highly electro-positive metal; 
as above set forth. 

14th. The use of metallic brushes, enfilmed with an amalgam 
of sodium or its equivalent; for incorporating together particles 
of quicksilver, gold, silver, or any other metal, scattered through¬ 
out ores, slimes, or any other materials; as above set forth. 

15th. The more convenient transportation, handling and sub¬ 
division of quicksilver; by conversion into solid forms ; in the 
manner herein substantially described. 


12 


H. Wurti on Sodium Amalgamation. 


Editorial Note .—At the session of the National Academy of 
Sciences held in Washington in January last, Prof. Silliman read 
a paper upon the sodium amalgamation, detailing the results of 
a series of experiments conducted by him upon a scale of suf¬ 
ficient magnitude to test the value of this discovery upon gold 
quartz. In one experiment made on over 500 pounds of low 
grade ores, worth about $15 per ton, the sodium amalgam ex¬ 
tracted practically all the gold not existing in the sulphids. 
This experiment was conducted in a large-sized Freiberg amal¬ 
gamator and was continued through one hour, the sodium 
amalgam being added in four successive portions of one ounce 
each, dissolved in a portion of the 20 pounds of mercury em¬ 
ployed. The loss in mercury was about one ounce in this ex¬ 
periment, the quantity of the sodium amalgam being 1*2 per 
cent of the total quantity of mercury in use. 

In a second series of experiments conducted on carefully pre¬ 
pared samples of richer ore, worth $820 per ton, treated in a 
revolving barrel, the saving by ordinary mercury was from 40 
to 60 per cent of the total quantity of gold present. With the 
aid of sodium amalgam 83*8 per cent were recovered. The re¬ 
sults in the large way in actual practice would probably be 
more satisfactory than those last named. Prof. S. stated that 
experiments had also been set on foot in California to test this 
process on a large scale in the actual working of quartz mills. 
The results of these experiments will be noticed hereafter. 




